Electron space discharge device



Oct. 23, 1951 w. w. SALDARlNl ELECTRON SPACE DISCHARGE DEVICE 4 Sheets-Sheet 1 Filed Jan. 26, 1949 Oct. 23, 1951 w. w. SALDARlNl 2,572,055

ELECTRON SPACE DISCHARGE DEVICE Filed Jan. 26, 1949 4 Sheets-Sheet 3 L5, FIE J5 JEJN 5 J TTOR NE I Oct. 23, 1951 w. w. SALDARINI 2,572,055

ELECTRON SPACE DISCHARGE DEVICE Filed Jan. 26, 1949 4 Sheets-Sheet 4 W 14/. 51% 04mm /ITTORNEY Patented Oct. 23, 1951 ELECTRON SPACE DISCHARGE DEVICE Walter W. Saldarini, White Plains, N. Y., assignor to Sonotone Corporation, Elmsford, N. Y., a corporation of New York Application January 28, 1949, Serial No. 72,809

9 Claims.

This invention relates to electron space discharge devices in which an electrode assembly comprising an anode, a cathode and at least one grid or control electrode interposed between the cathode and the anode, are enclosed in a hermetically sealed, generally-tubular envelope, and more particularly to such electron discharge devices which are known commercially as subminiature electron tubes," although some of the features of the invention are applicable to electron space discharge tubes other than subminiature tubes.

Among the objects of the invention are subminiature tubes of the foregoing type in which the envelope is provided with a novel arrangement of lead-in wires sealed through a transverse, generally flat envelope portion of the tubular envelope, which makes it possible to give such tubes great ruggedness, essential in applications such as in proximity fuses, in which the elements of the tube are subjected to enormous accelerating strains, the electrode lead arrangement simplifying also the manufacture of such tubes on a mass production basis and making it possible to align all external lead portions which serve as terminal connections to the electrodes of the tube, as a row of contact prongs, which may be readily inserted or removed from a flat socket structure, in which the socket terminals are likewise arranged in a compact row formation.

The foregoing and other objects of the invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawings, wherein:

Fig. 1 is a vertical cross-sectional view of one form of a multi-electrode subminiature tube exemplifying the invention, the tube being shown in a scale of about 1 to 8;

Fig. 2 is a cross-sectional view of the tube along line 2-2 of Fig. 1;

Fig. 3 is a vertical cross-sectional and partially elevational view of the same tube along line 3-3 of Fig. 1;

Figs. 4 and 5 are cross-sectional views along lines 44 and 5-5- of Fig. 1, respectively, Fig.

5 showing the bottom spacer in phantom by dash-dot lines;

Fig. 4-A is a plan view of the upper spacer of the tube;

Fig. 6 is a perspective view of the electrode assembly of the tube, as seen from the top;

Fig. '7 is a perspective view of the bottom part of the electrode assembly:

Fig. 8 is an elevational view of the transverse, flat end wall or stem of the tube envelope with the electrode contact leads sealed therethrough before their inner ends are joined to the electrodes of the electrode assembly;

Fig. 9 is a top view of the end row or stem shown in Fig. 8;

Figs. 10 and 11 are elevational and plan views of the anode structure of the tube shown in Figs. 1 to 7;

Figs. 12 and 13 are elevational and plan views of the auxiliary electrode of the tube shown in Figs. 1 to 7;

Fig. 14 is an elevational view with parts broken away, showing the relative positions of the stem with the electrode assembly united thereto, and the glass envelope, as they are held on the carrier collar of a sealing head in the process of fusing and hermetically joining the periphery of the stem to the open end of the tube envelope;

Fig. 15 is a view similar to Fig. 14, showing the glass envelope with the full length of the exhaust stem connected to the upper end thereof, both formed of a glass tubing of the same diameter, the stem with the electrode assembly being shown positioned in the open end of the envelope;

Fig. 16 is a view similar to Fig. 15 in a rightangular plane thereto;

Fig. 17 is a plan view of the carrier collar of Fig. 15, with the envelope and electrode assembly removed;

Figs. 18-A, 18-13 and 18-0 are enlarged detail views similar to Fig. 16, showing the successive stages of the process of fusing the stem of the electrode assembly;

Fig. 19 is a vertical cross-sectional view of the sealing machine used in fusing and sealing the stem to the envelope; and

Fig. 19A is a plan view of the top portion of the sealing head of Fig. 19.

There are many applications requiring multielectrode electron amplifier tubes of the subminiature type, having extremely small dimensions and able to operate with a high degree of efliciency and with uniform desirable operating characteristics. Among such applications are hearing-aid amplifiers, proximity fuses, and radio broadcast receivers of a miniature size suitable for hidden wear in the pocket of the user, and other applications in which a minimum of space is a critical factor. Although the principles of the invention are applicable to other types of subminiature tubes, and some aspects of the invention are of a broader scope, their application will be described in connection with a 3 pentode-type tube shown in Figs. 1 through '7, which has a very wide use as a voltage gain and power amplifier.

The tube shown comprises an evacuated, generally elongated tubular envelope H of vitreous material such as glass, which encloses an electrode assembly generally designated it, having a plurality of electrodes which are connected to a plurality of leads l2, l3, l3, i and I5 hermetically sealed through an electrically insulated terminal end wall portion or stem I9 of the envelope to provide external circuit connections to the electrodes. The terminal end wall portion or stem I9 is made in the form of a waferlike stem of vitreous material sealed around portions of lead conductors l3 to IT, held generally aligned in a plane vertical to the plane of the stem. The wafer-like lead stem i9 extends in a direction transverse to the envelope and is fused to its lower end border.

The electrode assembly is similar to that described and claimed in the H. B. Jacobus, Jr., application, Ser. No. 72,985, filed on January 26, 1949, issued as Patent No. 2,572,031 on October 23, 1951, and assigned to the assignee of the present application. It comprises a filamentary cathode 2|, a control grid 22, a screen grid 23, and an anode 23, all extending longitudinally generally parallel to a common axis of the electrode assembly, and two electron-intercepting shield electrodes 25, 25 interposed across the electron path between the anode 24 and the screen grid 23. The cathode 2| is made of a thin filament of a refractory metal such as tungsten. provided with the usual electron-emitting coating. The two grids 22, 23 are made of fine refractory wire wound around and held secured to two pairs of grid side rods or posts 28, 29, respectively. The anode is made in the form of a general cylindrical tubular member of metal having at the upper and lower edges tongue-like junction ends 35, 33 each provided with a seating shoulder 36.

The two auxiliary shield electrodes 25, 26 are made of strips of refractory sheet metal which extends transversely across the path of electrons from the cathode 2| across the two grid electrodes 22, 23 toward'the facing portions of the anode 24. The central wall portion of each shield electrode has an elongated electron beam opening 42 for passing a beam of electrons from the cathode to the anode. Each of the two shield electrodes 25, 26 has two wings 43 bent inwardly toward the outer grid post 29 and arranged so that when the two shield electrodes are maintained at the cathode potential, the flow of electrons from the cathode to the anode will be confined to the two beam openings 42.

. The several electrodes of the electrode assembly are held in their operative position by two similar, generally fiat, sheet-lik spacers 3|, 32 made of a material having a high dielectric constant such as mica, one of the spacers being shown in detail in Fig. 4-A.

The two spacers 3|, 32 are designed to retain all electrodes in their assembled operative positions at the desired close-critical-spacing. To this end, the two spacers 3| and 32 are shown provided with openings for receiving and positioning the opposite junction ends of the two pairs of grid side rods 28, 29; slits 34 for receiving and positioning the opposite junction ends 31 of the two shielding sheet electrodes 25, 2B;

insulating 7 and peripheral recesses 33 shaped for interlocking engagement with the opposite junction end tongues 34, 35 of the anode. Each of the insulating sheet spacers 3|, 32 is also provided with resilient yieldable spacer projections 39 which engage the inner surface of the generally cylindrical tubular envelope H and serve to maintain the anode and the entire electrode assembly in the properly spaced and axially aligned position within the envelope when the electrode assembly is placed therein, from the open bottom end thereof, before the stem portion i8 of the electrode assembly is sealed to the side walls of the envelope ll.

Each of the two spacers 3|, 32 has a central opening 44, shown as being of triangular shape, to provide at the vertex of two angular edges thereof an angular seating recess against which spaced seating portions of the filamentary cathode 2| are held biased so as to keep the main active portion of the cathode 2| in the proper tensioned operative position. The opposite end portions of the filamentary cathode 2| are pro.- vided with junction elements or tabs 27 through which the end portions of the cathode are secured to connector elements by means of which the cathode is held tensioned and biased against the seating recesses of the two cathode seating openings 44.

As seen in Figs. 3, 5 and 7, the bottom junction tab 21 of the cathode is secured to the end of one arm of a generally L-shaped connector strip 45, the other arm 41 of which is secured in aligned overlapping engagement with the bottom junction tongue 37 of the shield electrode 25. As seen in Figs. 1, 3, 4 and 6, the upper cathode connector structure is formed by a U-shaped support rod 5| and a coil spring 52 seated on one arm of the rod 5|. One arm of the U-shaped rod 5| is aflixed as by welding to the upper junction tongue 3| of the shield electrode 26. The coil spring 52 has a plurality of helical-turns coiled loosely around the outer arm of the connector rod 5|. One arm end 53 of the coil spring is restrained from movement by affixing it, as by welding, to the inner arm of the rod 5|. The other end of the loose coil spring 52 terminates in a substantially straight, relatively long spring arm 53 to the end of which is secured, as by welding, the upper junction tab 21 of the cathode 2|. The special connector arrangement shown simplifies the proper alignment and mounting of the connector elements to the associated supporting elements of the cathode assembly, in positions in which the free spring arm 54, and the free connector arm 46, keep the cathode tensioned and biased against the angular seating recesses of the two cathode seating openings M, so as to maintain the cathode properly tensioned in its aligned operative position.

The upper junction tongue 35 of the tubular anode 34 has secured thereto a metallic getter support strip 5| having formed therein a pocket 62 holding a body of getter material and facing the adjacent side wall portion of the envelope. so as to substantially prevent getter-vapor from materially reducing the surface leakage resistance of the insulating spacer 3|.

In accordance with the present invention, an electrode assembly of the general type described above is combined with a transverse end wall or stem portion of the envelope which also serves as a socket therefor, and which is provided with a plurality of sealed-in conductor leads, some of which are generally aligned in a row along the central portion of the end wall and some of which are placed transversely of the row of leads to assure that when the end wall is heated and then cooled in the process of fusing it to the side walls of the envelope, the strains are distributed substantially uniformly and that no excessive strain shall be introduced in the end wall stem structure. Furthermore, in accordance with the invention, outward lead portions of the generally aligned row of sealed-through conductor leads are utilized as a row of prong terminals through which the several electrodes of the electrode assembly are connected to external circuits, inward lead portions of at least two of the prong-terminal leads being connected to inward lead extensions of the transversely positioned leads, which inward lead extensions provide substantially straight, axially-parallel connectors to facing electrode junction elements of the electrode assembly.

Figs. 8 and 9 show one form of an end wall or stem with the sealed-in leads, for exemplifying one application of the principles of the invention. The generally circular flat end wall I9, of refractory material such as glass, has sealed therethrough a plurality of leads I2 through II, generally arranged in a row along the center of the stem, and two trans. ersely disposed additional leads ll, I8 sealed through stem portions at opposite sides of the row in outward portions of the stem corresponding to the outward positions of the leads I2 and I6. With this arrangement, the additional leads I], I8 represent a row of leads aligned in a plane generally transverse to the row of leads I2 through I6.

As seen in Fig. 9, the sealed-through lead portions of leads I3, I5 are slightly displaced from the plane, of the row of leads which they form with leads I2, I4, and I8, so as to increase the relatively close spacing between the sealedthrough portions of the row of leads I2 through I6, and to reduce the glass strains when the refractory glass body of the stem is heated to fusion temperature when fusing its outer boundary to the side wall of the envelope and then cooled in the process of joining them into a continuous hermetically-sealed envelope structure.

In the practical form of the invention, the leads I2 to I8 are made of wires having a low coeiiicient of expansion which may be readily fused to glass and form therewith a vacuumtight hermetical seal, such wires being known as Dumet wires and being formed of an alloy of nickel and iron and coated with oxidized copper to provide good adhesion to glass of the type used in vacuum-tight envelopes of amplifier tubes.

With the stem arrangement of the invention described above, the inward portions of the leads may be readily so arranged that a substantially straight or slightly bent lead portion extending from the stern in a direction generally parallel to the axis of the electrode assembly will provide a lead connection from the electrode to the external circuits. This assures a clean combined electrode and stem assembly, with all connector elements extending between the electrode assembly and the external terminal connections being readily accessible for manipulation, and joining by welding or the like. In addition, this arrangement greatly increases the ruggedness of the combined electrode assembly, and gives all interconnecting elements between the electrode assembly and the base greatly increased structural strength for withstanding the strains imposed thereon when such tube is exposed to the enormous acceleration forces in applications such as proximity fuses on projectiles.

In the form shown, the ends of the inward portions of leads II, I5 and I6, which are parts of the main row of terminal leads I2 through It, and the adjacent junction ends of the grid side rod 28 of the inner grid 22, the Junction end of grid side rod 28 of the outer grid 23, and the June. tion tongue 35 of the anode, respectively, all extend substantially parallel to the axis of the electrode assembly.

The inward portions of the two lead II, II, which are aligned in a row which is generally transverse to the main row of leads I2 through I 6, likewise extend into engagement with the junction ends I! of the two shield electrodes 25, 28, to provide connections to the two shield electrodes and therethrough to the filamentary cathode H, the opposite ends of which are connected between shield electrode 25 and shield electrode 26.

The inward portions of the several leads I3, II, I6, I1, I8, terminate substantially in a plane transverse to the tube axis, so that the inner ends of the several leads may be readily aligned adjacent the junction elements of the electrodes to which they are to be Joined and respectively secured thereto by simple welding operations.

The outward portions of leads II, IO, which are aligned in a plane transverse to the plane of the main row of leads I2 through I6, are cut off slightly beyond the outer flat surface of the stem I! as they emerge therefrom.

To provide external terminal connections to the electrodes to which the inward lead portions I'|, I8 are connected, the inner portions of leads I2 and I 4 are bent to form connector elements which join their outward prong portions to the inward lead portions II, I8, which provide the connections to the shield electrodes described above. It will be noted that the inwardl bent portions I2, I3 extend near the inner flat surface of the stem I9 at a sufilcient distance therefrom to permit easy welding of the bent ends of the inner leads I2, I3 to the straight inner portions of leads l1, l8.

By securing the inner ends of the several electrode leads I3, I5, I6, I! and I8, which are displaced from a plane, to the junction portion of the electrode assembly at points where they emerge beyond the outer surface of the bottom spacer 32, the ends of the inner lead extensions serve also as retainers which retain the lower spacer 32 against axial displacement relatively to the electrode assembly.

Figs. 14 to 18-C, inclusive, show one manner of fusing and hermetically sealing the vitreous glass stem of the electrode assembly to the open end portion of the tubular envelope structure of the tube of the invention. In prior-art subminiature tubes, the exhaust tubulation is usually connected to the upper end of the glass envelope of the tube, and it is usually of smaller cross-section than the cross-section of the envelope. As shown in Fig. 15, in manufacturing the sub-miniature tube of the invention, the tubular tube envelope as well as the tubular exhaust tubulation, are made from a single glass tubing of the same cross-sectional dimension, a straight piece of glass tubing 'II of the proper quality of glass being heated to form thereon a neck portion I2 of reduced diameter through which the exhaust tubulation 1| is con- 'nected to the envelope portion II of the tube.

The top portion I3 01' the tube envelope II by which it is joined to the neck portion 12 of the exhaust tubulation II, is shaped to extend substantially perpendicularly or only at a slight angle to the axis of the tubing, so that after the tube is exhausted by means of the exhaust tubulation H, the tube may be sealed off at the junction of the neck portion 12 and the top portion 13, leav= ing a negligibly short sealing tip protrusion on th a top wall portion 13 of the envelope.

When proceeding to seal the glass stem Id of the electrode assembly to the envelope H, the electrode assembly is placed in the envelope with its glass stem l8 held within the open end of the envelope, so that a short end portion 14 overlaps and extends beyond the outer surface of the stem 58 (as seen in Figs. 15, 16 and 18). A mechanism of the type conventionally used for sealing the leads of midget amplifier tubes to their glass envelopes, may be readily modified for fusing the open end of the envelope to the glass stem of the electrode assembly placed in overlapped relation, in the manner shown in Figs. 15, 16 and 18.

Referring to Fig. 19, such conventional sealing machine usually comprises a rotatable turret l rotated by a suitable machine around a vertical axis, the turret carrying along its periphery a plurality of spaced revolvably mounted sealing heads it. The sealing heads it shown, are of a generally conventional shape, and comprise a frame structure having two transverse frame members ll, 38 structurally joined by uprights 79, 8|, the lower frame member 58 having a downwardly extending shaft 82 arranged to revolve within a bearing sleeve 83 of the turret, so that a rotary motion may be imparted to the heads, as through a gear 86 secured to the shaft 92 and engaging a driving gear 85 driven by a motor mechanism mounted in a conventional way in the base or turret of the machine.

Two clamping jaws 96, 81 for selectively clamping therebetween the envelope (Fig. 19-A) are slidably mounted between two guide members 88, 89 secured to the upper ends of the uprights 19, M of the sealing head frame. The laterally extending guide portions of each clamping jaw 86, 8'! which are slidably guided between the two guide members 88, 89 are provided with follower pins 9| engaging cam slots 92 of a cam member 93 guided in a suitably shaped arcuate guide channel of the upper guide member 89, so that by imparting an arcuate motion to the cam member 93, the clamping jaws 86, 81 may be selectively actuated to release or clamp the envelope H. The cam member 93 is operated in a conventional way as by an actuating rod revolvably mounted in a hollow center portion of the upright 8i and connected through a crank 94 to the cam member (Fig. 19-A) On the central bore of the upper frame member 11 is mounted a tubular collar member 95 provided along its upper generally horizontal end surface with transverse upwardly tapered ridge projections 96 extending outwardly from the central hollow space 91 of the collar 95, the

inner end portions of the two seating ridges 99 being provided with raised seating projections 98 projecting above the level of the seating ridges 96. Although only two opposite seating ridges 96 and seating projections 91 are shown provided on the carrier collar 95 of the sealing head, three or more angularly spaced peripherally arranged seating ridges and seating projections may be provided on the upper end surface of such collar for holding seated thereon the lower surface of the glass stem l8 of the electrode assembly and the lower edge of the glass envelope II, when they are rotated with the head during the process of fusing the overlapping end portion of the envelope to the glass stem I8.

It should be noted that the outer surface of the stem l8 of the tube surrounded by the envelope II is slightly tapered in upward direction, giving its outer surface a slightly conical shape. In the practical form of the tube of the invention the axial inclination of the outer surface of the stem 18 is about 1% degrees.

With the envelope H and the lead stem I8 of the tube so held positioned on the seating ridges 98 and the seating projections 98, and retained thereon by the clamping jaws 86, 81 of the head, the downwardly facing surface of the stem i8 and the lower portion of the envelope ll surround the stem are exposed to the heating action, for instance of gas jets indicated by dash-double-dot arrow 99 (indicated in Figs. 15 to 19). In other words, the gas jets are so located as to direct the heating flames against the bottom surface of the stem 18 and the lower portion of the envelope il surrounding the stem, the outward ends of the electrode leads 53, Hi, i5, i6 and H projecting into the openings or slits of the collar so as to protect them against excessive heating and cause them to carry away heat reaching the stem to portions of the collar engaged thereby.

Since it is also desirable to reduce the amount of heat transmitted by the stem to the electrode assembly, and in particular to the lower mica spacer 92 thereof, it is sufficient to make only one or at most only three of the inwardly. extending portions of the leads terminate directly below the lower outer surface of the lower mica spacer 32. Under the action of the heating flames applied to the rotating overlapping portions of the bottom portion of the envelope II and the stem is surrounded thereby, the glass body of the heated envelope becomes plastic and because of its surface tension, it contracts and fuses as it contracts with the adjacent surface portions of the stem, which have likewise been.

brought to fusing temperature (Figs. 18-A to l8-C show the successive stages of the fusing process) when so fusing and hermetically sealing the lower portion of the envelope to the outer surface portions of the glass stem surrounded thereby.

Throughout each period during which the envelope and stem are heated to fusion temperature, an atmosphere of carbon dioxide is maintained within the interior of the envelope. The alkaline earth coating originally applied to the cathode consists of alkaline earth' carbonate, or a mixture of alkaline earth carbonate, alkaline earth nitrate, and alkaline earth hydroxide. When such coating is heated in an atmosphere of carbon dioxide, the carbon dioxide forms with the alkaline earth compound of the coating, alkaline earth carbonate, and poisoning of the alkaline earth coating such as would occur in the presence of an ordinary atmosphere or inert gases other than carbon dioxide, is suppressed and substantially prevented. The carbon dioxide is supplied to the tube by a supply duct connected to the open upper end of the exhaust tubulation, as by a cup-shaped member at the end of the tube 80, as shown in Fig. 19.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific exemplifications thereof will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended claimsthey shall notbe limited to the specific exemplifications of the invention described above.

What is claimed is:

1. In an electron space discharge device having an assembly of electrodes extending longitudinally generally parallel to a common axis, a generally-tubular hermetically-sealed envelope coaxial with and enclosing the electrode assembly and having a transverse, generally-flat end wall of electrically-insulating refractory material; a set of at least four electrically conducting leads, including a pair of outer leads, all generally aligned in a row and sealed through said end wall and providing external contact prongs for said electrodes; at least one additional pair of electrically-conducting leads held sealed and fixed within two opposite outer portions oi said end wall and generally aligned in a plane transverse to said row, said electrodes having two junction ends generally extending toward and connected to inward portions of said additional pair of leads; and additional electrode junction ends generally extending toward and connected to inward portions of the other leads of said set; at least two inward portions of said set 01' leads being bent and connected to said inward portions of said additional pair of leads, substantially all 01' said additional leads projecting from said end wall being confined within the interior of said envelope.

2. In an electron space discharge device having an assembly of electrodes extending longitudinally generally parallel to a common axis, a generally cylindrical hermetically-sealed envelope coaxial with and enclosing the electrode assembly and having a transverse, generally-fiat, substantially circular and wall of electrically-insulating refractory material; a set 01' at least four electrically conducting leads including a pair of outer leads, all generally aligned in a row and sealed through said end wall and providing external contact prongs for said electrodes; at least i one additional pair of electrically-conducting leads sealed through two opposite outer portions of said end wall and generally aligned in a plane transverse to said row, said electrodes having two junction ends generally extending toward and connected to inward portions of said additional pair of leads; and additional junction ends generally extending toward and connected to inward portions of the leads of said set; at least two inward portions of said set of leads being bent and connected to said inward portions 01' said additional pair of leads, substantially all of said additional leads projecting from said end wall being confined within the interior of said envelope.

3. In a generally-cylindrical hermeticallysealed envelope of an electron space discharge device having an assembly of electrodes extending longitudinally generally parallel to a common axis, a generally-fiat, substantially-circular end wall of electrically-insulating refractory material extending transversely to said axis and constituting the sole base of the envelope; a set of at least four electrically conducting leads including apair of outer leads and all generally aligned in a row and sealed through said end wall and providing external contact prongs for said electrodes; at least one additional pair of electrically conducting leads sealed through two opposite outer portions of said end wall and generally aligned in a plane transverse to said row, said electrodes having two junction ends generally extending toward and connected to inward portions or said additional pair of leads. and additional junction ends generally extending toward and connected to inward portions 01' the leads of said set, at least two inward portions 0! said setoi leads being bent and connected to said inward portions of said additional pair of leads, substantially all of said additional leads projecting from said end wall being confined within the interior of said envelope.

4. In a space discharge device as claimed in claim 1, in which said electrode assembly comprises a generally tubular anode or sheet material, two spaced sheet metal electrodes racing opposite inner surface portions or said anodes, a generally-central filamentary cathode having opposite end portions connected to opposite end portions of diilerent ones or said two sheet electrodes, and at least one grid electrode or generally oblong cross-section interposed between said additional sheet electrodes and said cathode, said two sheet electrodes having each a Junetion end connected to said additional pair of leads, said anode and said grid electrode having each a junction end connected to a lead of said set. a I

5. In a space discharge device as claimed in claim 1, in which said electrode assembly comprises a generally tubular anode of sheet material, two spaced sheet metal electrodes lacing opposite inner surface portions 01' said anodes, a generally-central filamentary cathode having opposite end portions connected to opposite end portions of diflerent ones or said two sheet electrodes, at least two coaxial grid electrodes each of substantially oblong cross-section and each having an electrode junction end facing said end wall. said two sheet electrodes having each a Junetion end connected to said additional pairs of leads, said anode and said two grid electrodes having each a junction end connected to a lead 01' said set.

6. In a space discharge device as claimed in claim 5, in which alternate sealed-through lead portions oi said set are slightly displaced relative to the others for increasing the spacing between them.

'7. In an electron space discharge device having an assembly oi electrodes extending longitudinally generally parallel to a common axis, a generally-tubular hermetically sealed envelope coaxial with and enclosing the electrode assembly and having a transverse, generally-flat end wall of electrically-insulating refractory material; a set of at least five electrically conducting leads, all generally aligned in a row and sealed through said end wall and providing external contact prongs for said electrodes; the sealed through lead portions of alternate leads 01' said row 01' leads which are united to said end wall being laterally slightly displaced relative to the other sealed through lead portions of said row for increasing the insulating spacing between sealedthrough lead portions of adjacent leads, and reducing the strain to which said end wall is sublected when fusing it to adjacent portions of said envelope, the lateral displacement between adjacent sealed-in lead portions being suiliciently small for maintaining the external prong end portions of said leads aligned substantially in a row.

8. In a space discharge device having an assembly of electrodes extending longitudinally generally parallel to a common axis, a generally tubular hermetically sealed envelope coaxial with l1 and enclosing the electrode assembly and having a transverse generally flat end wall of electrically insulated material; a set of at least five electrically conducting leads, all generally aligned in a row and sealed through said end wall and providing external contact prongs for said =electrodes; the sealed through lead portiom of al ternate leads of said row of leads which are united to said end wall being laterally slightly displaced relative to the other sealed through lead portions of said row for increasing the insulating spacing between sealed through lead portions of adjacent leads and reducing the strain to which said end wall is subjected when fusing it to adjacent portions of said envelope, the lateral displacement between adjacent sealed in lead portions being suflioiently small for maintaining the external.

prong end portions of said leads aligned substantially in a row; at least one additional pair of electrically conducting leads sealed within opposite outer portions of said end wall and generally aligned in a plane transverse to said row,

said electrodes having two junction ends extend-- 9. In a space discharge device as claimed in as claim 8, said electrode assembly including an anode; two spaced sheet metal electrodes facing opposite inner surface portions of said anode, a

generally-central filamentary cathode having opposite end portions connected to opposite end portions of different ones of said two sheet electrodes, at least two coaxial grid electrodes each of substantially oblong cross-section and each having an electrode junction end facing said end wall, said two sheet electrodes having each a junction end connected to said additional pair of leads, said anode and said two grid electrodes having each a junction end connected to a lead of said set.

WALTER W. SALDARINI.

REFERENCES CITED The following references are of record in'the file of this patent:

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